I am also having the same issue when adding a server in Cluster Manager:
```
An unhandled exception occured
Traceback (most recent call last):
File "/usr/local/lib/python2.7/dist-packages/flask/app.py", line 1612, in full_dispatch_request
rv = self.dispatch_request()
File "/usr/local/lib/python2.7/dist-packages/flask/app.py", line 1598, in dispatch_request
return self.view_functions[rule.endpoint](**req.view_args)
File "/usr/local/lib/python2.7/dist-packages/flask_login/utils.py", line 261, in decorated_view
return func(*args, **kwargs)
File "/usr/local/lib/python2.7/dist-packages/clustermgr/views/server.py", line 77, in index
if server_exist:
NameError: global name 'server_exist' is not defined
```